Concepts Elicit Actions Direct Evidence

The reported evidence supports the view that concepts are residuates of perceptual experiences. The information accessed most easily is that relevant for typical actions, but depending on the situation we may access information useful for less typical actions. Thus action experiences are reflected in concepts, but the evidence available thus far does not lead to the conclusion that motor information is automatically activated.

Neuroimaging studies and behavioral studies support the hypothesis that some kinds of motor information are directly elicited by concept-nouns. It has been demonstrated, for example, that action is a powerful cue for recalling information on objects. Magnie, Ferreira, Giuliano, and

Poncet (1999) report the case of an agnosic patient who recognized only objects with which he could recall associated actions - tools, kitchen utensils, clothes, body parts - but not animals and musical instruments (he didn't play any instrument).

Neuroimaging. Neuroimaging studies show that object knowledge is organized as a distributed system. In this system object attributes are stored near the same modality-specific areas that are active as objects are being experienced (Martin, Ungerleider, & Haxby, 2001; Pulvermiiller, 1999). This goes against the claim, defended by widely accepted theories regarding concept organization and representation in the brain, that conceptual information is functionally and physically independent of modality-specific input and output representations and that the appropriate level of analysis for studying conceptual organization is that of whole categories, not of features (Mahon & Caramazza, in press). PET indicated that naming of tools, compared to naming of animals (importantly, animals were large four-legged animals, such as elephants), differentially activated the left middle temporal gyrus, an area very close to the area assumed to store information about object movement, which is also activated by action-generation tasks, and the left premotor cortex, generally activated when participants imagine themselves grasping objects with their dominant hand (Martin, Wiggs, Ungerleider, & Haxby, 1996). This suggests that action and manipulation information is automatically activated by viewing objects and pictures, and that the same areas are involved when forming motor imagery and when activating information on tools. Using fMRI, Simmons, Pecher, Hamann, Zeelenberg, and Barsalou (2003) show that brain activation during a verification task of modal properties (Pecher, Zeelenberg, & Barsalou, 2003) reflects the processed properties but is also distributed in different areas. In particular, in trials with motor properties, many areas are active, particularly visual areas. This evidence supports a close relationship between visual and motor properties.

Behavioral. Behavioral studies support the hypothesis that motor information is directly activated in the processing of concept-nouns. Borghi et al. (in press) demonstrated with a part-verification task that concept-nouns of object parts directly activate the motor system. Sentences such as "There is a horse in front of you" were followed by parts chosen so that actions directed toward them (on the real object) required a movement upward (the head of the horse) or downward (the hoof of the horse). Responding by pressing a button in a direction compatible with the part location (e.g., responding upward to verify that a horse has a head) was faster than responding in a direction incompatible with the part location.

Preliminary evidence by Borghi and Nicoletti indicates that processing artifacts activates the kind of grip appropriate to use them. Participants categorized words and pictures in natural and artifacts by pressing different buttons. Categorization times were slower for artifacts that are typically used with a precision and a power grip (e.g., harp), than for artifacts used with two power grips (e.g., rake).

What happens with concept-nouns that refer to objects with which we typically interact in different ways? Action intentions expressed linguistically may modulate the activation of the motor system. Glenberg and Kaschak (2002) asked participants to provide sensibility judgments by pressing a button either moving the hand towards the body or away from the body. They found a compatibility effect between the action to perform and the sentence to process: for example, the sentence "Close the drawer" was responded to more quickly while moving the hand away from the body, and the sentence "Open the drawer" while moving the hand toward the body.

Preliminary evidence by Borghi indicates that the movement performed influences judgments on size. Participants judged the size of objects requiring a precision grip (e.g., pencil) and a power grip (e.g., eggplants) in four conditions, when asked to move their hands in order to simulate a precision grip movement or a power grip movement and when asked to use pliers of two different sizes to mimic the same movements. Size ratings produced in the precision grip condition were lower than those produced in the power grip condition.

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